Nicotinic acid (Niacin) has been used for many years for the treatment of dyslipidemia. Indeed Niacin decreases triglycerides (TG) and low density lipoprotein cholesterol (LDL-c) but more importantly increases high density lipoprotein cholesterol (HDL-c). Although the drug has been used for so long, its precise mechanism of action remains elusive. The aim of this study was to characterise the metabolic changes induced by 8 week treatment with Niacin in dyslipidemic, overweight patients. The importance of the inhibition of lipolysis on the overall lipid effects of niacin will be studied. In order to get a very comprehensive view of all metabolic activities of niacin, this study will investigate the potential effects of niacin on Glucose metabolism, lipid and lipoprotein turnover, quantitative changes in lipoproteins and key enzymes involved in lipid metabolism.
24 patients will be included in a double blind placebo controlled cross-over 8 week study comparing placebo to Niaspan (a long release formulation of niacin). In order to prevent any drop out linked to the flushing side effect of niacin, patient will take aspirin (300mg) prior to treatment throughout the study duration. The study will include at start and end of each arm, a full lipoproteins quantification as well as a measure of enzymes involved in lipid metabolism. On day 42 and 56 of each period, after an administration of either placebo or 500mg of immediate release niacin respectively, changes in plasma free fatty acid levels will be measured for 8hours in order to assess potential loss of activity of niacin over time upon chronic treatment with niaspan. Half of the patient will have an exploration of their glucose metabolism using hyperinsulinic clamp technique, whereas in the other half a metabolic turnover study using stable isotopes will focus on their lipoproteins, triglycerides and cholesterol handling. These explorations will be done at the end of each treatment period.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
24
Voluntary men with mixed dyslipidemia and abdominal obesity will receive extended release nicotinic acid. The dose of niaspan will be up-titrated for 3 weeks starting at 500 mg/d in order to reach 2g/d at start of week 4 dose which will be continued until the end of week 8. After a wash-out period of 3 weeks, they will receive placebo for 8 weeks. According to their randomization arm, subjects will receive either in first place placebo followed by extended release nicotinic acid or the opposite.
Centre de Recherche en Nutrition Humaine
Nantes, France
Evolution of non-esterified fatty acid and triglycerides concentrations over time
Twelve hours after ingestion of chronic treatment, measures of non esterified fatty acid and triglycerides concentrations were carried out during 480 minutes to assess acute and chronic treatment effect on lipolysis and on triglyceride concentration. To appreciate both acute and chronic effects, subjects received medicinal supplements in addition to their chronic treatment: * On day 42, 500 mg of placebo to assess chronic nicotinic acid effect versus placebo effect * On day 56, 500 mg of immediate-release nicotinic acid (INA) to assess acute versus chronic nicotinic acid effect.
Time frame: After 42 and 56 days of placebo or nicotinic acid treatment
Insulin sensitivity after treatment
Euglycemic Hyperinsulinemic clamp with glucose tracer infusion
Time frame: After 53 days of placebo or nicotinic acid treatment
Lipoproteins metabolism
Stable Isotopic tracer infusion (d3-leucine, 13C-acétate, d5-glycerol)
Time frame: After 53 days of placebo or nicotinic acid treatment
Lipid profile
Measure of lipoproteins (VLDL, IDL, LDL, HDL) - characterization of lipoprotein's subfraction Measure of enzymatic activity of cholesteryl ester transfer protein (CETP), phospholipid transfer protein (PLTP) and lecithin cholesterol acyl transferase (LCAT)
Time frame: Before and after placebo or nicotinic acid treatment
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